Clamp assembly for use on screen printing machines



Oct. 31, 1967 M. L. JAFFA ETAL 3,349,698

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 3Sheets-Sheet 1 FIG! I JNVENTORS Marrhew L.Jaffa BY David Jaff'a ATTORNEY06b 1967 M. L. 'JAFFA ETAL 3,

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 3Sheets-Sheet 2 FIG.4

22 37A 32c K 970 13 INVENTORS Marrhew L. Jaffa David Jaffa ATTORNEY Oct.31, 1967 M. L. JAFFA ETAL 3,349,698

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 v5 Sheets-Sheet 5 INVENTORS I David Jaffa ATTORNEY Mafihew L. JaffaUnited States Patent 3,349,698 CLAMP ASSEMBLY FOR USE ON SCREEN PRINTINGMACHINES Matthew L. Jaifa, 92 Clark St., Rutherford, NJ. 07070, andDavid Jada, 38-26 Allwood Place, Fair Lawn, NJ. 07410 Filed Mar. 3,1965, Ser. No. 436,847 5 Claims. (Cl. 101-126) ABSTRACT OF THEDISCLOSURE This invention is directed to a screen printing machinehaving a frame on which an endless belt is mounted for indexing thematerial to be printed whereby the width of the belt defines theavailable printing area of the material to be supported thereon and aprinting carriage including a screen frame having a screen supportedthereon normally mounted on the machine frame for movement between aprinting and non-printing position wherein the improvement resides inthe utilization of a clamping means mounted on the machine frame and onthe printing carriage which is adapted to grip the printing belt so asto permit maximum utilization of the width of the belt for effecting ascreen print for a given size belt. This is attained by a clamping meanscomprising a fixed jaw member and a jaw member movably mounted withrespect thereto. The arrangement is such that each of the respective jawmember is provided with complementary inclined surfaces for gripping themarginal edge portion of the belt and whereby one of the jaw members isprovided with an outer surface which is rendered substantially flushwith the horizontal surface of the belt so as to enable maximumutilization of the belt width for a given size belt during operation ofthe screen printing machine.

This invention relates, in general, to a screen printing machine; andmore specifically to a novel clamping arrangement for use on a screenprinting machine.

In a screen printing machine, particularly of the type disclosed in acopending application Ser. No. 159,956, filed Dec. 18, 1961, now PatentNo. 3,199,449, the screen printing operation is performed on a movingprinting belt or blanket with the printing occurring as the belt andmaterial thereon is being indexed. As exemplified in the disclosure inthe above mentioned copending application the material to be printed isdisposed between a printing carriage, which carries the printing screen,and the printing belt or blanket. The arrangement is such that theprinting screen is rendered movable between a printing and nonprintingposition relative to the printing belt and material thereon.Accordingly, the moving belt functions both as the means for supportingthe material to be printed and as the means whereby the material isindexed so that successive printing operations may be performed on acontinuous strip of material. In this manner, a continuous strip ofmaterial may be successively printed with repeating designs or the like.

In such screen printing apparatuses a clamping means is usually disposedalong the frame of the machine on either side of the belt formaintaining the belt fixed to the frame as the carriage and the printingscreen carried thereon, is returned to its initial starting positionafter a printing operation has been completed. Cooperatively associatedwith the carriage are other clamping means which are adapted to engagethe belt when the printing screen carried thereon is lowered intoprinting position. Thus, the printing belt, carriage, and materialdisposed therebetween are secured in printing position to prohibitrelative movement therebetween during a printing and indexing operation.The belt, the carriage, and the material 'ice secured therebetween arethus simultaneously advanced or indexed in the direction of the belttravel during a screen printing operation by a suitable driving means.In operation when the first mentioned frame clamps are renderedinoperative the second mentioned carriage clamps are rendered operative,and when the carriage clamps are rendered inoperative, the frame clampsare rendered operative. In this manner the printing operation issimultaneously performed during the indexing operation of the material,with registration of succeeding designs or repeats being assured bypositive clamping means to secure the belt and material as the printingcarriage is returned to its initial starting position.

Heretofore, the known clamping construction, utilized for securing theprinting carriage to the belt during the printing operation, or forholding the belt fast when the printing carriage is returned to itsinitial start position upon the completon of a printing operation,greatly reduced or minimized the usual surface area of such printingblanket. For this reason the effective printing area of the material waslimited a corresponding amount. Heretofore, the largest known belt widththat can be employed with present known technology is approximately 115inches. Utilizing the known clamping constructions with such belt then,the maximum usable printing surface of the belt was normally reduced toa width of approximately inches to inches. The useful width of such beltwas reduced because the marginal portions of the belt were rendereduseless as a printing surface as this portion of the belt had to be usedas the portion to be gripped by clamping means to secure the belt. Theuseful surface area of the printing belt blanket was further restrictedby the width of the frame supporting the silk screen of the belt. Thus,with the known construction the useful width of a belt or blanket wasreduced by the width of the clamp necessary to secure the belt to eitherthe frame of the machine or to the printing carriage, and width of theframe supporting for the printing screen. Accordingly, the smaller widthbelts had their respective useful Working area proportionally reduced.

It is therefore the object of this invention to provide an improvedclamping arrangement whereby the useful printing surface of a printingbelt or blanket of a screen printing machine is enhanced withoutincreasing the overall standard widths of known printing belts.

It is another object of this invention to provide relatively simple andpositive acting clamp construction that is specifically adapted for useon screen printing machines to make it possible to use the maximumsurface area of a printing belt or blanket.

It is another object of the invention to provide a specific clampingarrangement constructed and arranged so as to enhance the usefulprinting area of a printing bed or blanket by approximately 10 percentwithout increasing the overall standard width of such belts or printingblankets.

Still another object of this invention is to provide a clampconstruction utilized in conjunction with a screen printing apparatuswhich underlies the frame of the printing screen so that the usefulwidth of the belt is not diminished by the width of the screen frame.

Another object of this invention is to ing arrangement whereby the widthor marginal portion of a printing belt o blanket heretofore reserved foraccommodating the width of a printing screen frame is now rendereduseful as a printing surface, and whereby the useful printing width orarea of the belt is enhanced by an amount approximating twice the widthof the screen printing frame.

In accordance with this invention, the foregoing objects, and otherfeatures and advantages are attained by providing a novel clampingassembly comprising of a means provide a clampfor mounting the clampmeans either to the frame of the screen printing machine, or to theprinting carriage mounted for movement along the frame of the machine.The clamping means fixed to the frame of the machine are cooperativelyassociated with respect to the belt so that when rendered operative, itmaintains the moving belt or printing blanket fixed relative to theframe of the machine. A similarly operating clamping assembly adapted tobe connected to the carriage, is cooperatively associated with the beltor blanket for securing the carriage thereto so that the carriage, thebelt, and the material disposed therebetween may be moved in unisondurind a screen printing and indexing operation as more particularly setforth in the copending patent application Ser. No. 159,956, filed Dec.18, 1961.

In accordance with this invention clamping means comprise a mountingmeans by which the clamping assembly is secured to its associatedstructure. The clamping assembly includes a fixed jaw member providedwith a substantially flat head portion disposed in substantiallycoplanar relationship with the upper surface of the printing belt orblanket. The fixed jaw is further provided with a downwardly inclinegripping surface which is disposed in overlying relationship to the topsurface of the printing belt or blanket. A movable jaw member is mountedfor movement toward and away from the fixed jaw member, and it isprovided with a complementary inclined gripping surface disposed beneaththe blanket. Thus movement of the movable jaw toward the fixed jawsecures the printing blanket therebetween in a manner so that thegripped portion of the belt is angled downwardly. If desired, a non-skidsurface may be disposed along the respective gripping surfaces of therespective jaws. A means in the form of a piston and cylinder assemblyis cooperatively associated with the movable jaw so as to effect theactuation thereof between clamping and unclamping position with respectto the belt disposed therebetween.

Accordingly, the arrangement of the clamping means relative to the beltis such that the clamping jaws grip the belt at an angle with respect tothe horizontal. Consequently, the arrangement is such that the frame ofthe printing screen overlies the gripping jaws so that both the width ofthe screen frame and the jaw members utilize or occupy the same marginalportion of the printing belt or blanket. For this reason the usefulsurface area of the printing blanket is enhanced by the width of thescreen printing frame. Accordingly the useful printing surface area ofthe belt is enhanced without increasing the standard width of a knownbelt construction. With the con struction described the width of apresent 115 inch wide printing belt or blanket can be increasedapproximately percent.

A feature of this invention resides in the provision of an improvedclamping assembly that is specifically adapted for use on a screenprinting machine wherein the respective clamping jaws thereof areprovided with complementary inclined surfaces for gripping therebetweena marginal portion of a printing belt or blanket so that in an operativeprinting position the width of a screen frame overlies the jaws of theclamp to enhance the use ful printing area of the belt by an amountequal to substantially twice the width of the screen printing frame.

Another feature of this invention resides in the provision whereby theclamping assembly is relatively simple in construction, positive inoperation, and which is particularly useful for application on screenprinting machines.

Other features and advantages will become more readily apparent whenconsidered in view of the drawings and description in which:

FIGURE 1 is a side elevation view of a clamp assembly adapted for use ona screen printing machine, wherein the clamping assembly is shown in theinoperative or open position.

FIGURE 2 is a right end view of the clamping assembly of FIGURE 1.

FIGURE 3 is a plan view of the clamping assembly of FIGURE 1.

FIGURE 4 illustrates an elevation view of a modified clamp constructionadapted for use on a screen printing machine wherein the clamp assemblyis illustrated in its closed or operative position.

FIGURE 5 is an end view of the clamping assembly of FIGURE 4.

FIGURE 6 is an elevation view of still another modified form of theinvention.

FIGURE 7 is an end view of the clamping assembly of FIGURE 6.

Referring to the drawings there is shown in FIGURES 1 to 3, a clampingassembly 10 which in accordance with this invention is adapted to beutilized on a screen printing apparatus of the type disclosed incopending application Ser. No. 159,956, filed Dec. 18, 1961. Briefly,the screen printing apparatus in the mentioned copending applicationcomprises a frame assembly 11 on which there is mounted over end rollersan endless printing belt or blanket 12. cooperatively associated withthe printing belt or blanket 12 is a carriage (not shown) which supportsthereon the printing screen 13 for movement between a raisednon-printing position and lowered printing position with respect to themoving belt or blanket. Accordingly, a clamping means 10 is required tomaintain the printing belt or blanket 12 fixed relative to the frameassembly 11 of the machine as the printing carriage and printing screen13 carried thereon are moved to their initial starting position afterthe completion of a printing operation to its initial start position.Also, the printing carriage is provided with clamping means adapted tofixedly secure the carriage to the printing blanket so that during theprinting operation, the printing blanket, the carriage and materialdisposed therebetween may be moved in unison to effect the printingoperation as the material is being indexed or advanced a distance equalto the repeat of the design to be printed as more fully set forth incopending application Ser. No. 159,956, filed Dec. 18, 1961. Since theinstant invention is merely concerned with the construction of theclamping assembly, a further detailed description of the screen printingapparatus is not considered to be pertinent to an understanding of theinvention herein described.

Referring more specifically to FIGURES 1 to 3, a clamping assembly 10disclosed is adapted to be secured to the frame 11 of the screenprinting apparatus. Accordingly, the clamping assembly 10 comprises amounting bracket 14 which is adapted to be suitably secured to theassociated frame 15 of a screen printing machine. As shown, the mountingbracket comprises a plate suitably fixed to the frame of a screenprinting machine. Connected to the extended end of the bracket 14 is therelatively fixed jaw member 16 of the clamping assembly. In theillustrated embodiment it is constructed as an inverted L-shaped memberhaving a substantially flat head portion 16A and a downwardly inclinedgripping surface 16B which defines with the flat head thereof a toe 17portion that extends in overlying relationship to the marginal portion12A of the printing belt or blanket 12. If desired, a suitable non-slipsurface 18, as for example, a rubber pad or the like may be suitablysecured to the inclined gripping surface 16B of the fixed clamp member16.

Supported on the bracket 14 for relative movement toward the fixed clampmember 16 is a movable jaw member 19. As shown, the movable jaw member19 is provided with a complementary inclined surface 19A which isadapted to be moved toward and away the inclined surface 16B of thefixed jaw member 16. The arrangement is such that the inclined surface19A of the movable jaw member 19 is disposed beneath the lower surfaceof the moving belt or blanket and it too may be provided with a non-skidsurface or pad 20. Means in the form of a piston and cylinder assembly21 is supported on the mounting bracket 14 so as to effect the movementof the movable jaw member 19 toward and away the fixed jaw member 16between clamping and non-clamping position. The arrangement is such thatin the clamping position of the belt 12, the marginal gripped portion12A of the belt is inclined downwardly between the respective inclinedsurfaces of the jaw members. In the operative or clamped position of theassembly, it is to be noted that the head 16A of the fixed jaw 16 memberis rendered substantially flush with the horizontal surface area of thebelt or blanket 12. Accordingly, the frame 22 of the printing screen 13in printing position is disposed over the flat head portion 16A of thefixed clamp member 16. In this manner the width of the printing screenframe 22 does not occupy any portion of the horizontal printing surfaceof the printing belt or blanket 12. For this reason, the width or usefulprinting area of the printing belt or blanket 12 can be enhanced bytwice the width of the printing screen frame 22, since the width of theprinting screen frame 22 does not occupy any portion of the horizontalarea of the belt. As the width of a printing frame 22 is 4 to 5 inches,it is to be noted that the useful width of a blanket resulting from theclamp construction herein described may be enhanced approximately 8 to10 inches, (i.e. twice the width of the screen frame). Thus, the usefulprinting surface of a belt can be substantially increased.

FIGURES 4 and 5 illustrate a modified form of the invention. In thisform of the invention the clamping assembly is adapted to connect to theprinting carriage of a screen printed and it comprises a mounting meansformed of a pair of spaced, angled structural members 31, 32 in whichthe vertical legs portion thereof are spaced from one another.Interconnected between the vertically spaced leg portion of the mountingmembers 31, 32 is channel member 33 to provide a base support for thepiston and cylinder assembly 34 to actuate the movable jaw member 35 aswill hereinafter be described. Fixed between the vertical legs of themounting means and adjacent the end of the channel 33 is a standard 36which extends upwardly therefrom. The fixed jaw member 37 of the clampis secured to the standard 36. Means in the form of a pin and slotconnection is provided to effect vertical adjustment of the fixed jawmember 37 along the standard 36. As shown, the standard 36 is providedwith an elongated slot 36A adapted to receive suitable fasteners 38 bywhich the fixed jaw member 37 may be adjustably secured thereto. 7 -'Thefixed jaw member37 comprises an inverted L shape member, having ahorizontal leg portion 37A and vertical leg portion 37B, the verticalleg portion 37B being adapted to receive to fasteners 38 by which it isadjustably fixed to the standard 36. The horizontal leg 37A is providedwith a flat top 37C and an inclined gripping surface 37D which inclinesdownwardly therefrom to define therebetween a toe portion that overliesa marginal portion 12A of a printing blanket 12. If desired, a non-skidsurface as for example, a rubber pad 39 or the like may be suitablysecured to the gripping surface of the fixed jaw member.

The movable jaw member is connected to a piston and cylinder assembly 34which is suitably supported on the channel base 33 disposed between theangled mounting means 31, 32. Accordingly, the piston 40 of thepistoncylinder assembly 34 is connected to the movable jaw member 35. Ashereinbefore described the movable jaw is provided with an inclinesurface 41 which complements the gripping surface 37D of the fixed jawmember. The movable jaw member 35 is disposed beneath the printingblanket 12, and it too provides a non-skid pad 42 or surface similar tothat of the fixed jaw 37. The arrangement is such, that when the pistonand cylinder assembly 34 is actuated, the movable member 35 is movedtoward or away the fixed member. Thus as described in reference to theFIGURES 1 and 3, the fixed jaw member 37 is disposed so that its flathead portion 37C is substantially in co-planar relationship to theprinting surface of the belt or blanket 12. Accordingly, the frame 22 ofthe printing screen 13 is disposed in overlying relationship to thefixed jaw member, thereby occupying the same portion of the belt as thegripping jaws. Thus the working area of the printing belt or blanket isnot reduced by the frame width of the printing screen.

FIGURES 6 and 7 illustrate still another modified form of the invention.In the form of the invention the clamp assembly 50 comprises a pair ofspaced, angled members 51, 52 in which the vertical leg portions arespaced from one another. Secured between the vertical leg portion of themounting means 51, 52 is a mounting block 53 which is provided with abore 54. A standard 55 is supported in the bore 54 and a set screw 56threaded through a tap opening formed in the side of the block 53 firmlysecures the standard 55 in position therein. Connected to the block 53is a vertical extending threaded stud 57 having a pair of adjusting nuts58, 59 threaded thereon. Accordingly, the adjusting nuts 58, 59 formpositioning means whereby a yoke 60 fitted on the stud 57 may beadjustably positioned in respect thereto. The yoke 60 is also providedwith an aperture to embrace the standard 55 and it is fixed thereto by asuitable pin or fastener 61. Accordingly, the standard 55 may bevertically adjusted by setting the position of the yoke 60 relative tothe threaded screw 57 by varying the set position of the locating nuts58, 59 thereon.

Fixed to the upper end of the standard 55 is an inclined jaw member 62which functions as the fixed jaw member of the clamping assembly 50. Ifdesired, a nonskid surface 63 may be suitably secured to the inclinedsurface of the fixed jaw member 62. A guide pin 64 may be connected tothe yoke 60 to extend upwardly therefrom.

Mounted on the base 65 between the mounting bracket members 51, 52 is apiston and cylinder assembly 66 which forms the support and actuator forthe movable jaw member 67. Accordingly, the movable jaw member 67comprises of a plate having an inclined surface to complement theincline of the fixed jaw member. If desired the movable jaw is alsoprovided with a non-skid surface 68. The arrangement is such that in theclamping position, the marginal portion 12A of the belt 12 is securelyheld at an angle with respect to the horizontal between the inclinedgripping surfaces of the respective jaw members 62, 67. Consequently,the arrangement is such that the frame 22 of the printing screen 13overlies the clamping jaw members and thereby does not minimize theuseful horizontal width or area. of the printing belt or blanket 12.

In operation the movable jaw 67 is guided by the guide pin 64 secured tothe yoke 60. Accordingly, in this form of the invention the elevation ofthe fixed jaw member 62 may be readily set by adjusting the yoke 60 andstandard 55 secured thereto by setting the positioning nuts 58, 59accordingly.

From the foregoing it will be readily apparent that the respectiveimproved clamping assemblies of the instant invention is such that theprinting blanket 12 is securely gripped during the printing operation ofthe screen printing machine, and in a manner so that the screen printingframe 22 occupies the same portion of the belt which is gripped by theclamping means. In this manner the maximum horizontal width of theprinting blanket of a given standard size is utilized.

While the instant invention has been described with reference to severalembodiments thereof, it will readily be understood and appreciated thatvariations and modifications thereof may be made without departing fromthe spirit or scope of the invention.

What is claimed is:

1. In combination a screen printing machine having a frame and anendless belt mounted on said frame for indexing a material to beprinted, the width of said belt defining the available printing area ofa material supported thereon and a printing carriage including a screenframe and screen supported on said screen frame movably mounted on saidmachine frame for movement between a printing and non-printing position,the improvement comprising a clamping assembly mounted on said frame andon said printing carriage, each of said clamping assemblies including:

(a) a mounting means,

(b) a fixed jaw member supported on said mounting means,

(c) a movable jaw movably mounted on said mounting means,

(d) means for moving said movable away from said fixed jaw,

(6) said fixed jaw and movable jaw having complementary inclinedgripping surface adapted for gripping the marginal edge portion of saidbelt therebetween, whereby said marginal edge portion is inclined to thehorizontal surface of said belt,

(f) and said fixed jaw having an outer surface substantially flush withthe horizontal surface of said belt so that said screen frame overliesthe outer surface of said fixed jaw when said screen frame is moved intoprinting position whereby a maximum portion of the belt for a given beltis rendered available for effecting a screen print.

2. The invention as defined in claim 1 and including means for effectingadjustment of said jaw members relative to said belt.

3. A clamping assembly adapted to be used in combination with an endlessprinting blanket of a screen printing machine and comprising:

(a) a mounting bracket including a mounting block,

said block having a bore therein,

(b) a vertical adjustment means connected to said block,

(c) a yoke adjustable connected to said vertical adjustment means,

(d) a movable jaw means including a standard carried by said yoke,

(c) said standard having its lower end receivable in said bore,

(f) an inclined jaw member fixed to the upper end of said standardwhereby the said fixed jaw member overlies a marginal portion of saidblanket,

(g) a movable jaw member, said movable jaw having an inclined surfaceunderlying said blanket,

(h) a piston and cylinder assembly mounted on said mounting bracket, thepiston of said piston and cylinder assembly being connected to saidmovable jaw for effecting the movement of said movable jaw toward saidfixed jaw for securing said blanket between said jaws when said pistonis actuated,

(i) and means for guiding the movement of said movable jaw.

4. A clamping assembly adapted to be used in combination with an endlessprinting blanket of a screen printing machine and comprising:

(a) a mounting bracket including a mounting block having a bore therein,

(b) a threaded stud connected to said block,

(c) a yoke adjustably mounted on said threaded stud,

(d) nut means threaded on said stud for setting the position of saidyoke thereon,

(e) a movable jaw means including a standard carried by said yoke,

jaw toward and (f) said standard having its lower end receivable in saidbore,

(g) a set screw for securing the standard in said bore,

(h) an inclined jaw member fixed to the upper end of said standardwhereby the said fixed jaw member overlies marginal portion of saidblanket, said fixed jaw having a flattened corner portion,

(i) a movable jaw member having a complementary inclined surfaceunderlying said blanket,

(j) a piston and cylinder assembly mounted on said mounting bracket, thepiston of said piston and cylinder assembly being connected to saidmovable jaw for effecting the movement of said movable jaw toward saidfixed jaw for securing said blanket between said jaws when said pistonis actuated,

(k) and means for guiding the movement of said movable jaw betweenclamping and unclamping position.

5. In combinaton, a screen printing machine having a movable printingblanket with predetermined area to define the printing surface of saidmachine, and a printing head including a printing screen movable intoprinting and non-printing relationship with said blanket, and saidprinting screen including a frame, the improvement of:

(a) a clamping assembly for securing the printing head to said printingblanket during a screen printing operating of the machine,

(b) said clamping assembly including a mounting means by which saidclamping assembly is fixedly secured to the printing head for movementtherewith,

(c) a standard fixed to said mounting means,

(d) a fixed jaw member,

(e) said jaw member having a fiat upper surface and gripping surfaceinclined relative to said fiat surface whereby with said grippingsurface overlies said blanket, said flat surface is disposedsubstantially coplanar with the surface of said blanket foraccommodating the frame of said screen,

(f) a movable jaw member,

(g) said movable jaw member having an inclined gripping surfaceunderlying said blanket,

(h) and means including a piston and cylinder assembly for moving saidmovable jaw member relative to said fixed jaw member to griptherebetween a marginal portion of said blanket, said marginal portionbeing inclined relative to the horizontal printing surface of saidblanket,

(i) the cylinder of said assembly being fixedly secured to said printinghead, and

(j) said movable jaw being carried on the piston of said piston andcylinder assembly.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/ 3 Australia.7/ 1948 Great Britain. 1/ 1955 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

J. R. FISHER, Assistant Examiner,

5. IN COMBINATION, A SCREEN PRINTING MACHINE HAVING A MOVABLE PRINTINGBLANKET WITH PREDETERMINED AREA TO DEFINE THE PRINTING SURFACE OF SAIDMACHINE, AND A PRINTING HEAD INCLUDING A PRINTING SCREEN MOVABLE INTOPRINTING AND NON-PRINTING RELATIONSHIP WITH SAID BLANKET, AND SAIDPRINTING SCREEN INCLUDING A FRAME, THE IMPROVEMENT OF: (A) A CLAMPINGASSEMBLY FOR SECURING THE PRINTING HEAD TO SAID PRINTING BLANKET DURINGA SCREEN PRINTING OPERATING OF THE MACHINE, (B) SAID CLAMPING ASSEMBLYINCLUDING A MOUNTING MEANS BY WHICH SAID CLAMPING ASSEMBLY IS FIXEDLYSECURED TO THE PRINTING HEAD FOR MOVEMENT THEREWITH, (C) A STANDARDFIXED TO SAID MOUNTING MEANS, (D) A FIXED JAW MEMBER, (E) SAID JAWMEMBER HAVING A FLAT UPPER SURFACE AND GRIPPING SURFACE INCLINEDRELATIVE TO SAID FLAT SURFACE WHEREBY WITH SAID GRIPPING SURFACEOVERLIES SAID BLANKET, SAID FLAT SURFACE IS DISPOSED SUBSTANTIALLYCOPLANAR WITH THE SURFACE OF SAID BLANKET FOR ACCOMMODATING THE FRAME OFSAID SCREEN, (F) A MOVABLE JAW MEMBER, (G) SAID MOVABLE JAW MEMBERHAVING AN INCLINED GRIPPING SURFACE UNDERLYING SAID BLANKET, (H) ANDMEANS INCLUDING A PISTON AND CYLINDER ASSEMBLY FOR MOVING SAID MOVABLEJAW MEMBER RELATIVE TO SAID FIXED JAW MEMBER TO GRIP THEREBETWEEN AMARGINAL PORTION OF SAID BLANKET, SAID MARGINAL PORTION BEING INCLINEDRELATIVE TO THE HORIZONTAL PRINTING SURFACE OF SAID BLANKET, (I) THECYLINDER OF SAID ASSEMBLY BEING FIXEDLY SECURED TO SAID PRINTING HEAD,AND (J) SAID MOVABLE JAW BEING CARRIED ON THE PISTON OF SAID PISTON ANDCYLINDER ASSEMBLY.